This is a proposal to determine the feasibility and therapeutic benefits of newly discovered benzamide derivatives (BAs) as mono-therapeutic agents or in combination with nucleoside analogues for the treatment of chronic hepatitis B. BAs were identified in our laboratory as inhibitors of hepatitis B virus (HBV) pregenomic (pg) RNA encapsidation, which is essential for the subsequent viral DNA synthesis. They are mechanistically distinct from, and should thus complement, the currently FDA-approved antiviral medications. In addition, inhibition of pgRNA encapsidation, or the nucleocapsid assembly, should not only preclude HBV genome replication and virion production, it might also disrupt the metabolism of HBV pgRNA-reverse transcriptase (RT) complex and core protein, which could consequentially interfere with the host innate antiviral immune response and cccDNA function in the infected hepatocytes. Unlike other pgRNA encapsidation inhibitors reported thus far, our benzamide pgRNA encapsidation inhibitors also effectively inhibit woodchuck hepatitis virus (WHV), which allows for the evaluation of the therapeutic benefits of this class of antivirals in a hepadnavirus chronically infected animal model for the first time. We, therefore, propose in this project to perform further lead optimization, and advance compounds with the most favorable ADME, safety and pharmacokinetic (PK) profiles for antiviral efficacy study in the WHV-infected woodchucks in vivo. Meanwhile, we will continue our efforts toward understanding the molecular mechanism by which BAs inhibit HBV nucleocapsid assembly and their consequential impacts on the interaction between HBV and its host hepatocytes. At the completion of this project, we will have a better understanding of the potential clinical benefits of pgRNA encapsidation-targeted antiviral therapy, either alone or in combination with nucleoside analogues in particular, and strategic insights in to the development of antiviral regimes for the cure of chronic hepatitis B infection in general. A decision on further preclinical/clinical development of the lead BAs compounds will be made accordingly.